In weapon systems of the soft recoil type wherein triggering of the firing mechanism is initiated while the gun tube is in an "out-of-battery" position, firing actuator devices have been employed which actuate the firing pin in response to sensing of the velocity of the gun tube moving into a pre-selected out-of-battery firing position.
The "out-of-battery" firing position of the gun tube is variable and is dependent upon the target zone requirement of a particular firing exercise.
Differences in zone firing requirement, i.e., firing to different zones, require propellant charges of different weights, e.g., range distances require different charges of different weights as do different trajectory apogees within the same range. Thus for long ranges and high trajectories within short ranges, the distance of movement of the gun tube to the firing position is longer than the distance of movement of the gun tube to the firing position where the ranges are shorter and the trajectories are shorter.
To vary the distance of movement of the gun tube to different firing positions and, thus, the zone settings of the system, a velocity sensing device is employed by which triggering of the firing pin is initiated by the sensing device in response to a pre-selected velocity of the gun tube having been reached in traveling to its "out-of-battery" firing position.